The present invention relates to physical therapy apparatus, and more particularly to a portable device for articulating a person's foot relative to the person's lower leg.
Therapeutic treatment of the human body may require motion to be induced in a specific part, for example, the ankle joint, for any of several reasons. Sickness, disease or injury may have caused a reduction in bodily functions, or may have left the patient unable to voluntarily move and exercise the muscles adjacent the joint. In some cases, a person can intentionally articulate a specific joint only if he or she can endure the resulting substantial pain.
It is well known that if there is no movement of a limb, the muscles therein will eventually atrophy. In some cases, muscle atrophy cannot be reversed by therapy and the atrophy seriously impedes use of the limb. Another problem with an immobilized limb is that the chances of a thrombosis occurring in the limb increase.
It is thus desirable to provide some mechanism for artificially inducing movement of a person's limb about a selected joint. One of the most complex joints which exist in any mammal is the human ankle joint which must be capable of sixty degree articulation under rather substantial loads. Many individuals suffer fractures of the ankle joint or experience traumatic injuries which result in bone chips in the ankle joint. These individuals must have their ankles encased in a cast for long periods of time. When the cast is removed, the muscles connected to the ankle joint, including the calf muscles, have usually undergone atrophy. In addition, there is usually an accompanying stiffness of the joint and surrounding tissues. Tenderness and a propensity for pain often make it uncomfortable for such a patient to articulate his or her own foot as part of a therapy program to restore muscle tone. Therefore, it would be desirable to have a compact, portable device which can be easily worn which artificially moves the foot relative to the ankle.
Heretofore, a number of apparatuses have been patented for articulating various portions of the human body, including the foot. U.S. Pat. No. 4,003,374 of Mizrachy discloses a device which may be used to move the foot of a patient who is anesthetized during surgery. An elongated frame which extends behind the leg has a strap at one end which surrounds the thigh of the patient and a hingedly mounted foot rest at its other end. A bellows positioned between the foot rest and a fixed vertical wall member is inflated and deflated through pneumatic circuitry not shown to move the patient's foot. Mizrachy also indicates that the foot rest can be moved by means of a motorized camming device, etc. Details of such mechanical drive mechanisms are not given.
U.S. Pat. No. 3,976,057 of Barclay discloses an apparatus for flexing the knee joint which includes a pair of straps which are wrapped around the calf and thigh, respectively. The straps are hingedly connected at the knee joint by mechanical linkages secured to the straps. These linkages are moved by pneumatic cylinders to articulate the knee. Somewhat similar to the device of Barclay is the device disclosed in U.S. Pat. No. 3,683,897 of Shield, et al.
U.S. Pat. No. 3,774,597 of Root discloses a device for artificially simulating the act of walking by holding a knee substantially stationary while sequentially elevating a heel of a foot associated with the knee, depressing the unsupported arch, and flexing the toes. U.S. Pat. No. 3,318,304 of Gurewich and U.S. Pat. No. 3,695,255 of Rodgers, et al. disclose mechanical devices which can be coupled to the foot of a hospital bed for simultaneously moving both of a patient's feet. U.S. Pat. No. 3,370,584 of Girtin discloses another device for simultaneously moving both of a person's feet. This device is mounted on a platform which appears to be supported on the floor but which could be supported on the mattress of a bed.
U.S. Pat. No. 3,323,518 of Swanson discloses a device for articulating a joint such as the elbow. It includes a cylinder or reciprocator whose ends are connected to straps which surround the forearm and bicep of a person's arm. The reciprocator includes a drive screw arrangement driven by a motor connected thereto by a flexible drive cable.
U.S. Pat. No. 3,917,261 of Small et al and U.S. Pat. No. 4,185,622 of Swanson disclose dual reciprocating foot rests. Finally, U.S. Pat. No. 3,742,940 of Phiffer discloses an oscillating foot rest which is reciprocable toward and away from a seat mounted on a base.
None of the patented devices discussed above provides a compact, portable device having a simple and reliable construction which may be comfortably fitted about the lower leg of a person for articulating his or her foot relative to the lower leg. In addition, none of the patented devices discussed above is readily adaptable for changing the stop and start points of the articulation as well as the total amount of articulation. Additionally, it would be desirable to have some mechanism in a foot articulating device that would better simulate the movement of a person's ankle joint than is provided in the patented devices above.